Communication Link Latency Compensation for Accurate Clock Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing clock synchronization protocols, such as Precision Time Protocol (PTP), assume symmetric transit delays between network devices, which leads to inaccuracies in clock synchronization for applications requiring high accuracy due to asymmetric latencies in transmit and receive paths.
Innovation Solution
A communication system measures and compensates for the asymmetry between transmit and receive path latencies using latency measurement and compensation circuitry, adjusting logical channel latencies to achieve more accurate clock synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clock synchronization protocols assume symmetric transit delays, then the protocol complexity is reduced and ease of operation is improved, but clock synchronization accuracy deteriorates due to asymmetric latencies in transmit and receive paths
Solution Approach 1:
The patent applies preliminary action by measuring the transmit path latency before performing clock synchronization. The source device measures the latency of the transmit path from source to destination using test packets, stores this measurement, and then uses it to compensate for asymmetric latency during actual PTP synchronization operations. This pre-measurement approach eliminates the need for complex real-time asymmetric latency calculations while maintaining high synchronization accuracy.
Solution Approach 2:
The patent introduces an intermediary mechanism by using a separate latency measurement path that acts as a mediator between the physical asymmetric communication channel and the PTP synchronization protocol. The measured transmit latency serves as an intermediary parameter that allows the PTP protocol to operate with simplified symmetric delay assumptions while still achieving accurate synchronization through compensation.
2Measurement precision
If asymmetric latency compensation is implemented, then clock synchronization accuracy is improved, but device complexity increases due to additional latency measurement and compensation circuitry
Solution Approach 1:
The patent extracts the latency measurement function as a separate, dedicated component within the PHY processor. By taking out the latency measurement and compensation logic from the main PTP processing path, the system achieves accurate asymmetric latency compensation while keeping the core synchronization protocol simple. The extracted latency measurement circuit operates independently and provides pre-computed compensation values to the PTP engine.
Solution Approach 2:
The source device performs self-service by autonomously measuring its own transmit path latency and using this measurement to compensate for asymmetric delays in its outgoing synchronization packets. The device serves itself by generating test packets, measuring the round-trip or one-way latency, storing the measurement, and applying the compensation without requiring external calibration or complex bidirectional measurement protocols.
Data Source
AI summary
To improve time synchronization in a communication network, a first communication device generates a measurement of a first latency of a transmit path of a communication link between the first communication device and a second communication device. The communication link also includes a receive path. The first communication device compensates for an asymmetry between the first latency of the transmit path and a second latency of the receive path using the measurement of the first latency.